Method and apparatus for continuous form grinding



y 1951 J. c. WILSON 2,554,079

METHOD AND APPARATUS FOR CONTINUOUS FORM GRINDING Filed June 10, 1948 5 Sheets-Sheet 1 INVENTOR ATTORNEYS May 22, 1951 J. C. WILSON METHOD AND APPARATUS FOR CONTINUOUS FORM GRINDING 5 Sheets-Sheet 2 June 10, 1948 Filed /N van/"ma t, 1.! inc [.f. If. Wk

JOHN CANILfiQN Arrommsvs May 1951 J. c. WILSON 2,554,079

METHOD AND APPARATUS FOR CONTINUOUS FORM GRINDING Filed June 10, 1948 llvvzm-orz JOHN G WILSON ATTORNEYS May 22, 1951 J. c. WILSON 2,554,079

METHOD AND APPARATUS FOR CONTINUOUS FORM GRINDING Filed June 10, 1.948

ATTORNn;

May 22, 1951 J. c. WILSON METHOD AND APPARATUS FOR CONTINUOUS FORM GRINDING E- Sheets-Sheet 5 Filed June 10, 1948 ATTOENEYS Patented May 22, 1951 METHOD AND APPARATUS FOR CONTINU- OUS FORM GRINDING John C. Wilson, Springfield, Ohio, assignor to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio Application June 10, 1948, Serial No. 32,123:

21 Claims. 1

The present invention deals with the grinding of certain articles intended to have a predetermined form, and is concerned primarily with the method and apparatus designed to provide a continuous process.

At the present time modern manufacturing processes call for the production of a large number of articles all of the same size and shape and which are intended to have a final finished form which can be achieved only by grinding.

The'present invention .is. predicated on the belief that manufacturing costs may be consider.- ably reduced if the grinding of such articles is carried out. as a continuous method.

The present invention has in view as its foremost objective the provision of a continuous grinding process which is characterized by the inclusion of the stepaof firmly positioning an article in an desired predetermined position as it passes a grinding station. This insures that the grinding will produce the proper form.

Still another object of the present invention is theprovision of a method of the character above indicated which includes the steps of initially loading the articles to be ground on a continuously moving conveyor, firmly positioning the articles as they pass the grinding station, and then releasing the articles to permit their discharge from the conveyor.

Various other more detailed objects and advantages of the invention that are associated with the method itself will in part become apparent and in part be hereinafter stated as the description proceeds.

Another highly important object of-the present invention is the provision of apparatus intended to effect continuous grinding and which consists essentially of a grinding station and an endless conveyor for taking the articles to be ground and moving them past the grinding station.

More in detail the invention has as an object the provision of apparatus of the type indicated which includes an endless conveyor provided with a plurality of work-holding units. Each of these units is designed to receive one or more of the articles to be ground.

Another highly important object of the invention is the provision, in continuous apparatus of the type indicated, of an'endless conveyor hav ing workeholding units of 'the type indicated and with. which are associated means for' rigidly clamping theworkpieces in position just'before they reach a grindingstation'and which means is released; at an.v appropriate. pointafter the articles have passedithe grinding'jstationrto.per-

mit of their discharge from the work-holding. units.

From the very nature of the operation being performed, it is highly important that each of the workpieces be properly positioned in the workholding unit as it passes the grinding station. If a workpiece should not be properly positioned, either at a point immediately before it reaches the grinding station. or at any time while the grinding operation takes place, it is desirable that the operation of the machine be immediately brought to a stop. Accordingly, a further object of the inventionis the provision, in a continuous grinding apparatus of the character aforesaid, of a'templet located immediately in advance of the grinding station and having oneormore openings exactly conforming to the shapeof the workpieces and the position which they are to assume in the grinding operation. Operatively associated with this templet is a. control switch which Will be actuated to stop the operation if any workpiece is not properly positioned as it passes through the templet.

Another object of the invention is the provision in continuous grinding apparatus of yieldable means for holding the workpieces in position at the grinding station and which means is operatively connected with the control switch aforesaid. Thus, if any workpiece becomes displaced from its proper position during the grinding operation, the limit switch will stop the operation.

In providing continuous grinding apparatus of the type with which this invention is concerned, it is important that the entire apparatus be under the ready control of the operator. Not only is it important that the automatic stops be providedas above indicated, but the operator must be able to reverse the operation so as to jog back any workpiece which mi ht be displaced and remove the condition which has caused the machine to stop. lie must be able to quickly startthe machine in operation.-

Accordingly, another highly important object of the invention is the provision, in continuous grinding apparatus of the type aforesaid, of control devices which may be available manually to start or stop the machine, automatically stop it if a workpiece is not properly positioned, and provide a reverse operation, if necessary; for eliminating a condition which stopped machine;

Various other more detail d objects and advantages oiithe inventioirsuch as arise in connection: with providing; pparatus. which. will carry outithe. above. noted idea i1l, in; part drawings become apparent and in part be hereinafter stated as the description of the invention pro- I ceeds.

The invention, therefore comprises a method and apparatus for carrying out a continuous grinding operation on a multiple of workpieces intended to have a final finished size and shape that is achieved by grinding.

For a full and more complete understanding of the invention reference may be had to the following description and accompanying drawings wherein:

Figure 1 is a view in side elevation of cntinuous grinding apparatus designed in accordance with the precepts of this invention;

Figure 2 is another side view similar to Figure l with outer casing parts removed and showing more particularly the endless conveyor;

Figure 3 is an enlarged detailed view partly in section and partly in elevation of the driving mechanism at one end of the conveyor;

Figure 4 is a similar view bringing out the takeup mechanism at the other end of the conveyor;

Figure 5 is a fragmentary showing of a portion of the conveyor at the bottom bringing out the workpiece releasing and discharge action;

Figure 6 is a transverse section taken normal to the showing of Figure 3 at the driving end, this view being taken about on the plane represented by the line 85 of Figure 3;

Figure 7 is an enlarged detailed transverse section through the work-holding units at the grinding station;

Figure 8 is an enlarged detailed section taken about on the plane represented by the line 88 of Figure '7;

Figure 9 is an enlarged detailed perspective view bringing out the position of the workpieces just before they reach the grinding station;

Figure 10 is a perspective similar to Figure 9 but showing the workpieces immediately after they leave the grinding station;

Figure 11 is an enlarged detailed perspective of one workpiece which may be continuously ground by the method and apparatus of this invention;

Figure 12 is a diagrammatic illustration of the control circuit; and

Figure 13 is a diagrammatic illustration of the hydraulic circuit used in controlling the hydraulic motor which drives the machine.

General arrangement The general arrangement of a continuous grinding machine designed in accordance with the teachings of this invention is depicted in Figure 1.

A bed is shown at It and this bed is adapted to rest on any suitable support. Carried by the bed Iii is a table I i and upstanding from the table ii is a supporting framework I2 which operatively supports the endless conveyor and associated instrumcntalities. This endless conveyor is referred to generally by the reference character C.

Upstanding from the table H is a column I3 and supported by the column I3 is a saddle I4 which is adjustable as to its height through the medium of a saddle extension I5 which is slidable in a way 55. A wheelhead i7 is carried by the saddle I4 and one or more grinding Wheels are operatively mounted in the wheelhead I T.

In the form of the invention illustrated in the emuveiy saaantdnn the-.wheelhead. Obviously gr' ding-wheels I8 and I9 are op on this particular number there is no limitation in the invention. Only a single wheel might be employed or a number in excess of two might be used.

A handwheel is shown at 29 and is operatively connected to the saddle extension I5 through the broken line connections shown at 2 i. This handwheel is availed of as a means to raise and lower the wheelhead I! in a manner well known in this art.

The wheels I3 and I9 may be driven from any appropriate source of power, although the invention has particularly in mind the use of an electric motor such as is represented diagrammatically at 22 in Figure 12. The actual driving of the wheels is not a part of the present invention and is conforming with well known practice in this art.

Referring now for the moment more particularly to Figure 11, one type of workpiece which may be ground by the apparatus hereof is illustrated. It is to be understood that the particular size and shape of this workpiece has no limitation of the invention. It is given purely for exemplary purposes.

The workpiece is designated W and in illustrated form is one of the vanes used in an air compressor of an electrical refrigerator. The workpiece W has a convex surface 23 and a concave surface 24, both of which are to be finished by a grinding operation. Outstanding from the side of the workpiece W are the trunnions 25 which, in the present instance, are used in corn junction with the means for holding the work piece in position, as will be later described.

The conveyor Referring now more particularly to Figures 2, 3, 4, and. 6, the endless conveyor C is shown as being in the form of a chain 26 which passes over sprockets 21 and 28. The sprocket 28 is the driving sprocket as shown in Figure 3 and is drivably mounted on a shaft 29 which also drivably carries aworm gear 30. Meshing with the worm gear 30 is a worm 3| that is drivably mounted on a shaft 32 that is carried by brackets 33. One end of the shaft 32 projects beyond the bracket 33 and drivably mounted thereon is another worm gear 34. Meshing with the worm gear 34 is a worm 35 drivably mounted on a shaft 35. The shaft 36 is journaled in the supporting struc ture I2 and its free end is drivably connected as by the driving connection shown at 31 to a hydraulic motor which is represented diagrammatically at 38. Hydraulic motors are well known as such and the particular details thereof are not a part of this invention. It suffices to point out that the hydraulic motor 33 is effective through connection 31, shaft 36, worm 35, worm gear 34, shaft 32, worm i, worm gear 30, and shaft 29 to drive the sprocket 28.

Referring now more particularly to the left hand side of Figure 2 which is considered in conjunction with Figure 4, it will be noted that the sprocket 21 is mounted on a shaft 39 that is J'ournaled at each side in blocks 40 that are slidably mounted between guides 4| that are anchored to the supporting framework. Each block 46 carries a screw stem 42 which is passed through a nut 43. that is anchored to a part of the framework. Obviously the nuts 43 may be rotated to cause rectilinear movement on the part of the shaft 42 and thus impart a similar movement to the blocks 40 and shaft 39. Thus, a.takeup for the chain 23 is provided.

It? W111 be noted that a pair 'di" curved guides egstmoreare -locatedi at each: end of. themachine: for a: purpose noww to. be: described. The chain. 26 carries acplurality: of workholding units: each of whichiis -designated'illl Each of the units U'h'as a pair: of f cars 45-. dependingfrom the bottom thereof with each pair of'ears. pivotally con.- n'ectedtoone'of the pivotal connections-"of the chainizfi as shown at 46. Thus, each workholding' unit'U ispivotal-ly. mounted on. the" chain; Each workholdingj unit? U. has a. pair of side flanges: 41 extending'outwardly from each. side thereof? which are received. beneath the guides 44 at eachendiof themachine-and properlyiguid'e theunitas-the turn. is being'made. Each work: holding unit'U is designedto hold a pair. of the workpieces W'in side by siderelationz Asisisho'wnin Figure 6 one of the; workpieces W has its: convex surface 231 inthe uppermost position: in x which it" is exposed to the grinding wheel I8, the edge of which has ashapecor.- responding to this: convex. surface- Onvthe other hand, the next; adjacent workpieceW has .a. con; cave surface exposed for cooperation with the grinding wheel [9.

Asis pointed out-more clearly;in Figures 7 and 8 each of the .unitsfU is. provided with a pair. 'of ears '48 whichupstand from the top. face. thereof, each of which cars is formed witha notch at 49; There are a pair of ears 48 at each end ofeach block and a pair at the center of each block. Each notch 49 on the-ears-"at the end is intended to receive one. of. the trunnions of the. workpiece, while thenotchesAB on. the central ears eachreceive the trunnions from theworkpieces onbothsidesthereof. A plunger. 59 isassociated with each central ear 48. Each plunger 50 carries a billil at the top which cooperates with thenotch 49 ingrippingatrunnion 25.-

Each plunger 58' is biasedv downwardly by. an

expansion coil spring..52,which isdisposed about the plunger and which engages a flange 53 there on at one. end and a shoulder 54' off the unitU at the other. end. Ateach end 'of. the block there is a pair of plungers 9, each havinga bill adapted to cooperate with the notch 49 of'an end ear 48 with which each plunger is associated;

Each plunger S'is cut away at one side and the unit U. is correspondingly cut away to-provide recesses 8 that accommodate springs 1. that actuate the plungers 9;

The lower. end of the plungers 50. and 9 are rounded to provide surfaces at 55"whichare adapted for cooperation. witha cam 551 The cam 56 is located inadvance of the grinding station. Thus, as'the plunger-s 5B ride onto the" cam. the bills'5l are upraised" which per.- mitsof'thepositioning of the workpieces W with the trunnions 25 received in the notches 49. Just before the. grinding station is reached' the plungers' ride off the cam 56, whereupon the springs 52 and I urge theplungei'sdownwardly to. cause the, bills 5! to grippingly engage the trunnions 25 and'firmly position the work.

Referring now more particularly to. Figure 5, itwillibe noted that another cam51is. located at the bottom ofthe framework I2. andhas its cam face downwardly exposed; Also aniendl'e'ss conveyor for taking finished workpieces is shown at 58; After each unit U leavesv the grinding station itipasses around beneath the'guidesM andas it approaches the cam 51 the rounded ends'55'of theplungers 50and9 rideonto the cam 51, thereby causing the bills 5l'to become spaced from" the notches 49 and'- to release the workpieces. W The latter their. fall. onto. the.

Automatic: stop.

Referring now more particularly to Figures 10 and. 1'1,,the' grinding station' is represented generallyfby' the reference character G. At the grinding stations G the framework supports spaced side bars 59 and 58, both of which are cut'awaysto provide corner notches; shown at 6| that accommodate the side flanges 47" of the units. U." Extending between the side bars 59 an'd'fifi is a top' plate 62 which is yieldably held in? position by springs 63'. and. headed studs 64. This'icover62 is provided with a pair of slots 55. and 66" which. accommodate the grinding wheelsiBand'lB. Itisevident thatif any of the workpieces W are disarranged' at the grinding station G, that isibeneaththeicover 62, the latter may be moved upwardly as such movement is permitted by the springs 63 1 and studs 64.

A control-switch"is--represented at 67 and may beof any type of-controlswitch now well known totheele'ctrical arts: The switch iii-includes; as itsoperating member, a plunger BB -whibh'iyengaged by -anarm iiil drivablymounted" on a shaft 1n; Alsodrivablycarried bythe shaft-mare a pairof arms H which engage fingers '52 which upstand from thecover 62-. Thus, if the cover 62 is movedupwardly as bythedisarrangement of a workpiece W, oneor bothofthe fingers Ii-will be moved upwardly to -IOtate the shaft lil and thus cause as. corresponding movement of the arms-69 This causes =operation-of the plunger SW-anclthereby effects: the switch BT- to stop the operation of the machine in a manner I to be later described;

Depending from-the'shaft 'lfi -is a templet- 13 that is formed with a-pair of openings M -and 15 designed to accurately conform to the shape of thew-orkpieces-Win theposition in which they are intendedtoassum'e in the grinding station. Thus; if each workpiece-W isproperly positioned it wiil passthrough the respective openings-M and*'l5"-'-'without affecting the templet. However, should' either-o-f these pieces-be not properly p0- sitioned'itwill strike'against the templet; the

- latterwi-ll'swing, and thesha-ft H3 rocked to rap der the control switch til-effective;

Hydraulic circuit Referring now more particularlyto FiguresZ andtl3; the hydraul-ic circuit for controlling operation of the motor 38*will be described. A fourwa-y valve isreferredto in its entirety by the referencecharacter V. It comprise a cylindrical casing 'ifi having'heads 'HandJB. Slidable in th'e'casing lfi is' a piston lli formed With' anannular groove imi A solenoid 8! has a plunger 82 connected by-a rod flt wit-h the piston 79: Likewise, a second solenoid 84 has a-plunger' 85 connected by a rod 86'with' the'piston 19; Therods 83'and 86 pass-through appropriate openings-in theheads Ti andl8. A pump for building up pressure is shown at 87. A service line '88 conn'ects the pump to the casing 16 substantially intermediate the ends thereof. A pressure tank is shown at 89 and is-connected by'a conduit 90 to the pump 8?. Another conduit 91 extends from the pressure tank' to conduits 92' and'93 whichlead into the casing le-atports on opposite sides-cf the piston I9 when the latter is'equidistantly spaced'betweenthe heads" and 18.

A=service line- Qd'eXtend from oneside of the motor iii-to a port in the casing l6 and another service 1ine95-extends from the other ide-of the motor to-anctherport inthe casing; When the piston 19 lisin-its midivayipo'siticpa-iioth the'serw ice lines 94 and 95 are blocked off and the motor is inoperative. When the solenoid 8| is energized the piston I9 is shifted in one direction to cause the hydraulic medium under pressure to be supplied to the motor M and drive the latter in the normal direction of operation of the machine.

It will be noted that a pair of springs 96 and 9'! are associated with the plungers 02 and 85. Thus, when the solenoid (ii is de-energized these springs will return the piston I9 to it intermediate motor stopping position. The solenoid 84 may be energized to impart a reverse drive to the motor M to give a jog back as will be necessary when it is desired to straighten out a misplaced workpiece.

Control circuit Upon referring to Figure 12, it will be noted that a pair of power lines are represented at LI and L2. Extending between these power lines is a line 90 including a manually operable switch 99 and a normally closed switch I00. Also included in the line 90 is the motor 22 which drives the grinding wheels I and I9. It is evident that if both of the switches 99 and I00 are closed the motor 22 will be energized to drive the grinding wheels. Another line IOI extends across the power lines. Included in this line [BI is a normally closed jog back switch I02, a manually operable switch I03, and a normally closed switch I04. It will be noted that the normally closed switch I04 is mechanically connected to the normally closed switch I00, so that when one is open the both are open. Both of these switches are mechanically connected-as indicated by the broken line to a plunger I05 of a solenoid I00. The solenoid I06 is connected across the power lines by a line I 07 going from one end of the plunger to the power line L2 and a second line I08 in which is included the switch 01 and a reset switch I09. An emergency stop switch H0 is connected in to bypass the switch 61 and energize the coil I06 when it is desired to stop the machine. A holding blade is represented at III and is connected to the line I08 by lines H2 and II3, to hold the machine in its stop condition until an undesirable condition has been eliminated and it is desired to again start the machine in operation.

The operation of the control circuit may be briefly described by noting that under normal conditions both the switches I00 and I94 are closed. When the operator is desirous of starting the grinding wheels into operation he closes the switch 99 and this completes the circuit to the motor 22. When he is desirous of starting the endless conveyor in its ordinary forward movement the switch I03 is closed. This energizes the coil 0|, whereupon the plunger 92 is aifected to shift the piston I9 and affects the valve V to start the motor 38 in the direction for normal operation of the machine.

If some of the workpiece W should not be in proper position as it reaches the templet I3 it will not pass through its respective openings I0 and I5 and the templet will be swung on the shaft "I0. A similar movement is imparted to the shaft I0 if any of the workpiece is improperly positioned beneath the cover 02. This rotation affects the switch 61 to close that switch and completes the circuit to the coil I09. As the latter is energized the plunger I05 is actuated to open both of the switches I00 and I04 and thereby stop the operation of. the grinding wheel and-the motor 22 and sewe age l .,.9 A ile. le ter, i s re ergized the valve V is returned to its neutral position, discontinuing the delivery of hydraulic power to the motor 38. Moreover, the holding plate III completes the circuit across the lines I I2 and I I3 to the coil I00 and maintains the open condition of the switches I00 and I04. Should the operator be desirous of jogging the conveyor backwards so as to eliminate the undesirable condition, he depresses the jog back switch I02. This switch instead of closing the line IOI now closes line H4 which includes the solenoid 84. The latter afiects the plunger to shift the piston I9 of the valve V to operate the motor 30 in a reverse direction. The operator will keep the switch I02 depressed as long as the reverse rotation is desired. Release of the switch will cause it to return to the position opening line I I3 and closing line IOI. When the machine is again ready for operation he first opens the reset switch I09 so as to de-energize the coil I00. This permits switches I00 and I04 to return to their normally closed position and the machine will again start into operation. If for any reason the operator should notice an emergency condition which requires stopping of the machine he merely presses switch IIO which has the same efiect as the automatic control switch 6'! because it completes the circuit to the coil I06 and thereby opens switches I00 and I04.

Operation It is believed unnecessary to here go into a detailed operation of the machine because the same has been described in connection with pointing out the functions of the various elements. It suffices to briefly outline the operation by noting that as each workholding unit U comes to the cam 50 the rounded ends 55 engage the cam surface to raise the plungers 50 and 9 and make each unit U ready for the reception of the workpieces W. The latter are now properly positioned and as the rounded ends 55 of the plungers 50 and 9 ride off the cam the workpieces are securely gripped between the bills 5| and the notches 09 of the ears 48. In this position they go through the grinding station G and are subjected to the action of the grinding wheels I8 and I9. After passing the grinding station they pass down to the under side of the. endless conveyor, whereupon the cam 51 releases the workpieces and they fall onto the endless conveyor 58. Obviously, each workpiece will have to be passed through the machine twice so that both the surfaces 23 and 29 thereof may be ground.

The machine is automatically stopped should any undesirable condition develop or the operator may stop it should an emergency arise by availing of the switch I I0.

While a preferred specific embodiment of the invention is hereinbefore set forth, it is to be clearly understood that the invention is not to be limited to the exact methods, apparatus, and devices illustrated and described, because various modifications of these details may be provided in putting the invention into practice within the purview of the appended claims.

I claim:

1. In continuous grinding apparatus, means forming a grinding station, an endless conveyor arranged in a formation providing substantially parallel top and bottom joined by a bend portion at each end, a plurality of workpiece holding units arranged in series and pivotally connected to said conveyor, workpiece holding means on "each pf; said units including multiple cam sur- 'in advance of said grinding station, cam means engageable by said cam surfaces for releasing saidhol'ding means and associated with the bottom of saidconveyorsubstantially adjacent one of said bend portions, and a conveyor for receiving workpieces released from the unit.

2. In continuous grinding apparatus of the character described, a workpiece holding unit comprising a body member, an ear upstanding i from said .body member and iormedwith a notch adapted to receive aportioniofa workpiece to be positioned in :said unit, aplunger reciprocably mounted in said body inclose proximity to said ear, a bill on said plunger complemental to said notch, and spring means associated with said plunger and body member for urging :said bill toward'said notch.

in continuous grinding apparatus of the character described, 'a workpiece holding unit comprising "a body imernber, an ear upstanding from: said body member and forme'd with anotch adapted to receive a portion of a workpiece to be positioned in said-unit, aplunger reciprocably mounted insai'dbody in'close proximity to said car, a bill on said plunger complemental tosaid inotchgspring means associated withsaid plunger and ib'o'dy member for urging said bill toward said notch, and a cam surface on the lower end of said"plunger'adapted for cooperation with a cam 'to raise said plunger against the influence 'ofssaid spring means.

4.'In continuous grinding apparatus of the character des'cribetl, la workpiece holding unit comprising a 'botly member havingan car upstanding from "each end thereof and a central ear-substantially in alignment with the-'first two ears, each of said ears being formed with a 'notch, a plurality of plungers operatively carried by said-body member, there being a plunger associated with each ear, each of-said plungers having a bill cornpl'emental to the notch in the 'respectiveear, and spring means associated'with said plunger and body member for urging said plungers in-a direction moving said bills toward said notches.

5. In continuous grinding apparatus of the character described, a workpiece holding unit comprising a "body member having'an car upstanding from each end thereof and a central ear substantiallyin alignment 'with the first two cars, each-ofsaidears being formed-with a-notch, 'a plurality of plungers operatively carried by said bod-ymember, there being a plunger associated 'witheach ear, each of said plungers having a bill compleme'ntal to the notch inthe re- :sp'ectiveear, spring means'assoc i'at'ed with said :p'lu'n'ger and body member for urging said plungers in :fa "direction moving said bills -towa'rd said notches, and a cam surface 'o'n-the-lower 'endof each'plunger adapted'to be engaged by a cam means to raise the respective plunger against the influence of said spring-means.

'6. -In continuous grinding apparatus, a workpiece holding unit comprising a body member, a

pair of ears upstanding from said body member at each end thereof and 'a third pair of cars upstanding from the body member substantially midway between the "cars at each end and in alignment ith'erewith, each of said ears being iormed with a notch adapted to receive afportion of a workpiece, a plunger operatively associated with each ear, a bill on each plunger complemental-to the respective notch, a spring for each plunger normally urging said plunger in a direction moving said bill toward said notch, and a cam surface at the end of each plunger remote from said bill.

7. In continuous grinding apparatus, a grinding station including a grinding wheel and means for driving :said grinding wheel, an endless conveyor,meansior driving said endless conveyor, a plurality of workpiece holding units arranged in series on said endless conveyor, holding means on each of said units adapted to grippingly engage a workpiece and properly position the same with respect to said grinding wheel, a control switch controlling the operation of said driving means for said grinding wheel and said conveyor, a templet located in advance of said grinding station and having an opening through which a properly positioned workpiece is adapted to pass, and operative connections between said templet and said switch whereby said templet is affected by an improperly positioned workpiece to" operate said switch and discontinue the drive to "said grinding wheel and conveyor.

8. =In continuousgrinding apparatus, a grinding stationincluding a grinding wheel and means iordriving said grinding wheel, an endless con- -veyor,-means for driving said endless conveyor, aplurality of workpiece holding units arranged in series on said endless conveyor, holding means onreaohof said units adapted to .grippingly engage a workpiece and properly position the same with respect to said'grinding wheel, a control switch governing the operation of said grinding wheeland conveyor, a top plate adapted to cover workpieces at said grinding station, said plate being yieldably held in position and operatively connected to said switch whereby an improperly positioned workpiece at said grinding station raises 'said plate to affect said switch to discontinue the drive to said grinding wheel and conveyor.

9. In continuous grinding apparatus, a grinding station includinga grinding wheel and means for driving said grinding wheel, an endless conveyor, means'for drivin said endless conveyor, aplurality of workpiece holding units arranged in :series on said endless conveyor, holding means on each of said units adapted to grippingly engage a workpiece and properly position the same with respect to said grinding wheel, a control switch governing the operation of said grinding wheel and said conveyor, instrumentalities located in advance of said grinding station operatively connected to said control switch and responsive to an improperly positioned workpiece to affect said control switch to discontinue the driveto said grinding wheel and conveyor, and additional instrumentalities located at said grinding station opratively connected to said switch and responsive to aniin'properly positioned workpiece at'said grinding station to afiect'said switch to "discontinue the drive to said grinding wheel and conveyor.

"IO/ in continuous grinding apparatus of the characterdescribedthe combination of an endles's conveyor, ahydraulic motor for driving said conveyor, a four-way valve controlling the operationo'f said motor, said valve including a piston whichnormally assumes an intermediate neutral position cutting off the delivery of fluid under pressure to said motor, and means selectively operable for moving said piston in either direction to cause the delivery of hydraulic medium under pressure to said motor in a proper direction to cause movement of said conveyor in any desired direction.

11. In continuous grinding apparatus of the character described the combination of an endless conveyor, a hydraulic motor for driving said conveyor, a four-way valve assembly for controlling the operation or" said motor, said assembly comprising a cylinder, a piston in said cylinder normally assumin an intermediate position therein discontinuing the delivery of hydraulic medium under pressure to said motor, a solenoid having a plunger operatively connected to said piston for moving said piston in one direction to cause hydraulic medium under pressure to be delivered to said motor to drive said conveyor in one direction, and a second solenoid including a plunger operatively connected to said piston for moving it in an opposite direction to cause said hydraulic medium under pressure to be delivered to said motor in an opposite direction and cause movement of said conveyor in an opposite direction.

12. In a continuous grinding apparatus of the character described the combination of an endless conveyor, a hydraulic motor for driving said conveyor, a four-way valve assembly for controlling the operation of said motor, said assembly comprising a cylinder, a piston in said cylinder normally assuming an intermediate position therein discontinuing the delivery of hydraulic medium under pressure to said motor, a solenoid having a plunger operatively connected to said piston for moving said piston in one direction to cause hydraulic medium under pressure to be delivered to said motor to drive said conveyor in one direction, a second solenoid including a plunger operatively connected to said piston for moving it in an opposite direction to cause said hydraulic medium under pressure to be delivered to said motor in an opposite direction and cause movement of said conveyor in an opposite direction, and spring means associated with each of said solenoids for causing said piston to assume its intermediate position upon deenergization of said solenoids.

13. In continuous grinding apparatus, a grinda o I r mg station including a grinding wheel and an electric motor for driving said wheel, an endless conveyor, a hydraulic motor for driving said conveyor, a hydraulic circuit for said motor including a control valve having a pair of solenoids associated therewith, and an electrical circuit for controlling the operation of said grinding wheel motor and said hydraulic motor, said circuit including a manually operable ,switch for said grinding wheel motor, a manually operable switch for energizing the solenoid which causes operation of said hydraulic motor to move it in its normal direction of operation, a pair of normally closed switches included in the circuits to said motor and solenoid, another solenoid having a plunger mechanically connected to said normally closed switches, and a control switch in the circuit to said last mentioned solenoid operatively connected with instrumentalities located at said grinding station to automatically energize said last mentioned solenoid as an incident to the improper positioning of a workpiece and thereby open both of the said normally closed switches and discontinue the operation of said grinding wheel motor and said hydraulic motor.

14. In continuous grinding apparatus, a grinding station including a grinding wheel and an electric motor for driving said wheel, an endless conveyor, a hydraulic motor for driving said conveyor, a hydraulic circuit for said motor including a control valve having a pair of solenoids associated therewith, and an electrical circuit for controlling the operation of said grinding wheel motor and said hydraulic motor, said circuit including a manually operable switch for said grinding wheel motor, a manually operable switch for energizing the solenoid which causes operation of said hydraulic motor to move it in its normal direction of operation, a pair of normally closed switches included in the circuits to said motor and solenoid, another solenoid having a plunger mechanically connected to said normally closed switches, a control switch in the circuit to said last mentioned solenoid operatively connected with instrumentality located at said grinding station to automatically energize said last mentioned solenoid as an incident to the improper positioning of a workpiece and thereby open both of the said normally closed switches and discontinue the operation of said grinding wheel motor and said hydraulic motor, and an emergency stop switch also included in the circuit to said last mentioned solenoid to energize said solenoid and open both of said normally closed switches should an emergency condition arise.

15. In continuous grinding apparatus, a grinding station including a grinding wheel and an electric motor for driving said wheel, an endless conveyor, a hydraulic motor for driving said conveyor, a hydraulic circuit for said motor including a control valve having a pair of solenoids associated therewith, and an electrical circuit for controlling the operation of said grinding wheel motor and said hydraulic motor, said circuit including a manually operable switch for said grinding wheel motor, a manually operable switch for energizing the solenoid which causes operation of said hydraulic motor to move it in its normal direction of operation, a pair of normally closed switches included in the circuits to said motor and solenoid, another solenoid having a plunger mechanically connected to said normally closed switches, a control switch in the circuit to said last mentioned solenoid operatively connected with instrumentalities located at said grinding station to automatically energize said last mentioned solenoid as an incident to the improper positioning of a workpiece and thereby open both of said normally closed switches and discontinue the operation of said grinding wheel motor and said hydraulic motor, a holding blade carried by the plunger of said last mentioned solenoid and adapted to complete the circuit thereto to hold both of said normally closed switches open, and a jog-back switch adapted to energize the other of the solenoids asosciated with said valve to cause said hydraulic motor to move said conveyor in a direction opposite to its normal direction of operation.

16. In the art of continuous grinding the method which includes the steps of (a) delivering workpieces to recesses in a continuously moving support; (b) providing a limited free travel path; (c) interrupting movement of the support in event workpieces fail to seat properly in said recesses and extend beyond the limits of the free travel path; (d) abrading the upper surface of supported pieces during a portion of the travel of said support; and (e) automaticall interrupting movement of said support in event workpieces become demounted by abrading action.

17. In apparatus for continuous grinding, the combination of, a grinding wheel, an endless conveyor positioned adjacent the periphery of said wheel with the path of travel of at least a portion of said conveyor normal to a radius line through said wheel and in line with the direction of rotation of said wheel, a plurality of workholding units having laterally extending side flanges pivotally mounted on said conveyor for movement between said conveyor and said wheel, arcuate guide means at each end of said conveyor in longitudinal alignment with said flanges for contacting the flanges of said units upon movement of said units across said guide means, and releasable means carried by each unit for grippingly engaging a workpiece.

18. In continuous grinding apparatus, a grinding station including a grinding wheel and means for driving said grinding wheel, an endless conveyor, means for driving said endless conveyor, a plurality of workpiece holding units arranged in series on said endless conveyor, holding means on each of said units adapted to grippingly enage a workpiece and properly position the same with respect to said grinding wheel, control means controlling operation of said conveyor and said means for driving said grinding wheel, template actuator means sensitive to correct positioning of a workpiece on said holding units and through which a workpiece passes in advance of said grinding station and movable by any improper positioning of a workpiece on a holding unit, and operative connections between said template actuator means and said control means actuating said control means upon movement of said template actuator means by any improper positioning of a workpiece on said holding unit to automatically stop said conveyor and the driving means for said grinding wheel.

19. In continuous grinding apparatus, a grinding station including a grinding wheel and means for driving said grinding Wheel, an endless conveyor, means for driving said endless conveyor, a plurality of workpiece holding units arranged in series on said endless conveyor, holding means on each of said units adapted to grippingl engage a workpiece and properly position the same with respect to said grinding wheel, control means controlling operation of said conveyor and said means for driving said grinding wheel, actuating means at said grinding station and engageable with a workpiece in the grinding station for continuously sensing the correct positioning of a workpiece in the grinding station and movable by any incorrect positioning of a workpiece in the grinding station, and operative connections between said control means and said actuating means operating said control means upon movement of said actuating means by any improper positioning of a workpiece at the grinding station to automatically stop said conveyor and said means for driving said grinding wheel.

20. In continuous grinding apparatus, a grinding station including a grinding wheel and means for driving said grinding wheel, an endless conveyor, means for driving said endless conveyor,

a plurality of workpiece holding units arranged in series on said endless conveyor, holding means on each of said units adapted to grippingly engage a workpiece and properly position the same with respect to said grinding wheel, control means controlling operation of said conveyor and said means for driving said grinding wheel, template actuator means sensitive to correct positioning of a workpiece on said holding units and through which a workpiece passes in advance of said grinding station and movable by any improper positioning of a workpiece on a holding unit, operative connections between said template actuator means and said control means actuating said control means upon movement of said template actuator means by an improper positioning of a workpiece on said holding unit to automatically stop said conveyor and the driving means for said grinding wheel, said drive means for said conveyor including means for reversely driving said conveyor, and a jog-back control means connected with said means for reversely driving said conveyor to render the same active.

21. In continuous grinding apparatus, a grinding station including a grinding wheel and means for driving said grinding wheel, an endless conveyor, means for driving said endless conveyor, a pluralit of workpiece holding units arranged in series on said endless conveyor, holding means on each of said units adapted to grippingly enage a workpiece and properly position the same with respect to said grinding wheel, control means controlling operation of said conveyor and said means for driving said grinding wheel, actuating means at said grinding station and engageable with a workpiece in the grinding station for continuously sensing the correct positioning of a workpiece in the grinding station and movable by any incorrect positioning of a workpiece in the grinding station, operative connections between said control means and said actuating means operating said control means upon movement of said actuating means by any improper positioning of a workpiece at the grinding station to automatically stop said conveyor and said means for driving said grinding wheel, said drive means for said conveyor including means for reversely driving said conveyor, and a jog-back control means connected with said means for reversely driving said conveyor to render the same active.

JOHN C. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 641,545 Richmond Jan. 16, 1900 665,661 Ketley et a1. Jan. 8, 1901 697,383 Milligan et al Apr. 8, 1902 1,142,700 Halstead June 8, 1915 1,886,878 Grob Nov. 8, 1932 1,897,049 Hawes Feb. 14, 1933 1,905,651 Raule Apr. 25, 1933 2,264,053 Russell Nov. 25, 1941 2,298,955 Mason et a1, Oct. 13, 1942 

